Earlier work in this laboratory demonstrated dose-related increments in visual reaction time performance and dose-related decrements in a two-flash detection task when nonaddict subjects received single doses of methadone. The performance deficit on the latter task was accompanied by significant alterations in stimulus-evoked responses recorded from scalp leads in the occipital region. Research in the literature indicates that opiate receptors are localized in numerous visual areas of the brain, including retina, ventral lateral geniculate, superior colliculus, visual pretectum and accessory optic system. Implicit times from stimulus to a-wave peak of the electroretinogram of man showed an increase with methadone. Work in progress includes determining the effects acute methadone and light stimulation on turnover of dopamine in retina and the effects of acute methadone on voluntary and involuntary eye movement control in man.